| Ganoderma lucidum is a precious medicinal fungus, which contains a variety of biological active substances, such as Ganoderma lucidum polysaccharide, triterpene compounds and has high P-glucosidase activity. Soybean isoflavone is the general name of polyphenol compounds in soybean, which is a secondary metabolite produced during the growth of soybean, has a variety of physiological functions. It is a new way to develop multi-factor health functional food to use Ganoderma mycelium containing ?-glucosidase for hydrolysis of isoflavone. The biological activity and bioavailability of isoflavone can be greatly improved by the conversion of flavonoids.In this paper, we studied the extracellular enzyme produced by liquid fermentation of Ganoderma lucidum. It was found that abundant enzymes including lignin degrading enzyme, cellulase, protease, amylase, anti oxidase, saccharifying enzyme and wood xylanase were produced by Ganoderma lucidum in fermentation process. In order to improve the utilization efficiency of the ?-glucosidase, four methods of homogenate processing, heating autolysis extraction, repeated freezing-thawing, and ultrasonic crushing were used to extract the ?-glucosidase from the ganoderma lucidum mycelia, and the extraction effect of different methods was compared. The results exhibited the best extraction method for ?-glucosidase extraction was the combination of homogenate processing and ultrasonic crushing. The mycelia form the fermented liquids needed to be treated by homogenate processing for 1 min in the ice bath, and then be treated 1min intermittent 1min for 5times by ultrasonic crushing in 200W. In this case, the total enzyme activity of the ?-glucosidase reached 3.116 U/mL, which increased by 112.26% than that of non-broken treatment.In order to improve the yield of bioactive substances and achieve industrial production of Ganoderma lucidum, stirred-tank bioreactor and air-lift bioreactor were used to cultivate Ganoderma lucidum to imitate fermentation conditions of shake flask culture, and fed-batch fermentation was used aside. Dynamic changes of mycelia biomass, residual sugar concentration,?-glucosidase activity Ganoderma polysaccharide content and intracellular triterpenoids yield were compared in different ways of fermentation. The results showed shake flask culture was imitated well by stirred-tank bioreactor for Ganoderma lucidum fermentation. Stirred-tank bioreactor was used to fed-batch fermentation, and the fermentation time of 8 days was determined. The measurement result of each index is:biomass 23.96g/L, P-glucosidase total activity 3.85U/mL, total polysaccharide content 5.89mg/mL, intracellular triterpenoids yield 822.26mg/L.In the experiment, the soybean isoflavone was transformed from glucoside hydrolysis to the free-type aglycone by the hydrolysis of Ganoderma lucidum from liquid fermentation. Through the optimization of the hydrolysis reaction conditions, the optimum process was determined for substrate concentration:34g/100mL, water quantity:10mL/100mL, temperature: 50?, time:36h. In this case, conversion rate of daidzin and genistin was 98.26% and 99.45%.The antioxidant activity of hydrolysis products were evaluated by anti-hydroxyl radical capacity, the DPPH scavenging capacity, the SOD enzyme activity, anti-superoxide anion radical capacity and the total antioxidant capacity. Results showed that each antioxidant index of hydrolysis products was significantly increased with the increasing of substrate concentration except anti-superoxide anion radical, and at the same substrate concentration, the anti-hydroxyl radical, the SOD activity, anti-superoxide anion radical and higher substrate concentration T-AOC activity were NO.4> NO.3> NO.2> NO.1. The results showed antioxidant capacity of soybean isoflavone aglycone was significantly higher than that of the untransformed glycoside, and the hydrolisis products with higher Ganoderma biological active substances showed higher antioxidant effect. |
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